The present invention relates to electric machines and, more particularly, to a multi-piece generator rotor including flat windings for generator fields.
In a conventional generator having a rotor and a stator, the rotor is provided with field windings that excite the generator while receiving a current from an exciting current source. The stator is provided with armature windings from which electrical power is obtained.
The rotor is typically provided with rotor spindles to effect rotation. With this structure, however, the spindles on each end of the rotor body require at least two sides of the field winding to be formed into an arc concentric with the spindle. This rotor construction including a one-piece rotor forging and end winding modules having curved ends is described in copending U.S. patent application Ser. No. 09/491,504, filed Jan. 26, 2000.
It would be desirable, for simplicity of manufacturing, to be able to flatten the curved sides of the prior end winding modules and thereby eliminate the need to form the arcs required for concentricity with the spindle.
In an exemplary embodiment of the invention, a multi-pole electric machine rotor includes a rotor body having poles with defined pole faces and parallel sides adjacent to the pole faces, a winding module that fits over the parallel sides of the poles, and a pair of spindles secured to respective ends of the rotor body and holding sides of the winding module to the rotor body. The spindles are preferably secured to the rotor body with bolts or threaded studs. Each of the spindles is provided with a notch shaped to receive one side of the winding module. In a preferred embodiment, the winding module includes a plurality of abutting flat field windings joined end-to-end and having openings sized to fit over the rotor body. The flat field windings may have a smaller perimeter at outside ends of the winding module that taper toward a largest perimeter at the middle of the winding module.
In another exemplary embodiment of the invention, a multi-pole electric machine includes a stator and the rotor of the present invention.
In still another exemplary embodiment of the invention, a method of constructing a generator rotor includes the steps of providing a rotor body having pole regions with defined pole faces and having parallel sides adjacent to the pole faces, fitting a winding module over the parallel sides of the rotor body, securing a pair of spindles to respective ends of the rotor body, and securing ends of the winding module to the spindles so as to thereby secure the ends of the winding module to the rotor body.